Grounded duplex telegraph system



5. 'l. CORY April 10, 1928.

GROUNDED D U PLEX TELEGRAPH SYSTEM Filed June 26. 1926 IN VEN TOR Luca/ Patented Apr. l0, 1 928. I

SAMUELI. CORY, on row'aco, NEW JERSEY, TELEGRAPH COMPANY, A

Ass Ie on TQ' AMERICAN TE riao ANJ) BIPORATIQN: 0E nE-vv- YORK.

GROUNDED DUPLEX 'TELEGRA sYsTEM. I

Application filed June '26 1926. s er-ialhltl'o. 1 18,75 3.

This invention relates to grounded duplex telegraph systems, and has as its object the provislon of improved arrangements for with telegraph sysreducing interference current power transtems from alternating mission systems.

It has been the practice heretofore to em ploy resonant shunts connected across the I recelving relay windings of telegraph systems of the class to which the invention're lates. These shunt circuits are'tuned 'to the frequency of the interfering power currents, offering a lowimpedance to these currents and a high impedance to the signaling ourrents. r

In accordance with the invention described hereinafter, I provide a novel'cir- 'cuit arrangement including a resonant shunt and affording complete protection against interfering power currents, as described more fully below.

3 the impedance to the The accompanying drawing shows'in diagrammatic form as an illustration, a differential telegraph repeater including a resonant shunt arranged according to my invention. The telegraph line, the balancing artificial line, the sending relay and. the connections therefor are old and Well understood in the art. The resonant shunt includes the capacity .C and the inductance L. In' the-receiving relay I connect one winding W in series with the line, and a second win-ding llV in series with the artificial line. I add a third winding of this receiving relay W, and connect this winding in series with capacity (land the inductance L of the resonant shunt. The capacity. of G, the inductance of L, and the resistances of L and the winding W", are so chosen that a relatively low impedance is offered to the interfering alternating currents and a relatively high signaling currents. The resonant at the frequency of the interfering power currents. With my arrangement, interfering currents flowing through the resonant shunt will flow through the third winding W of the receivshunt is, of course,

ing relay, and will neutralize the effect ofthe interfering currents flowing through the interfering current in "tem, a sending relay,

It will be understood that my improved arrangement affords a against interference in the ternating Y power currents. prictically no undesirable eifecton either ou goln or mcomin tele ra h si nals.

It is to be noted g g p b of the ordinary resonant shunt, protection is secured by making the impedance of the repeater from alshunt very lowa-t the interfering frequency,

Also it causes high protection f I that, whilein the case J with my improved arrangement protection.

is secured moreby neutralization than by shunting, and accordingly, comlng and outgoing signals is greatly reduced. t 7

What is claimed is; 4 p 1. In a grounded duplex telegraph system, a sending relay, l1ne, an artificial line, therebetween including an inductance and a capacity, said receiving relay including an operating winding and an additional winding in series with the inductance and capacity of the shunt path, sa d capacity being of such values that the shunt forms a tuned circuit resonant to in-' terfering alternating currents in the line and the effect on incoming andoutgoing signals is sl ight,the interfering current in the operating winding of the receiving relay being substantially neutralized by the flow of the ing. 7

2. In a grounded duplextelegraph system, a sendmg relay, a receiving relay, a

line, an artificial line, and a shunt path therebetween including an inductance and a capacity, said receiving relay having a plurality of operating windings and an ad'- ditionalwindingin series with the inductance and capacity included in the shunt path, said inductance andsaid capacity be ing of such values that the shunt/forms a tuned circuit resonant to interfering alternating currents in the line and the effect on incoming and outgoing signals is slight, the

the effect on in-:

said inductance and the additional windinterfering current in the operating windings of the receiving relay fermg current in the additional winding.

3.In a grounded duplex telegraph sysbeing substan- 'tially neutralized by the flow of the intera receiving relay, a p

line, an artificial line, and a shunt' path therebetween including an inductance and a capacity said receiving relay having a first winding in series with the line,fa secon 5 winding inseries with the "artificial line,

and a third winding in series with the inductance and capacityzincluded in the shunt ;name to this specification this 24th day of "June 1926. l

. 7 ath, said inductance and said capacity bemg-of such values thatthe shunt forms a 10 tuned circuit resonant to interfering alter--- terfering current nating currents in the line andthe effect on incoming and outgoing signals is slight, the interfering'current in the firstand second windings of the receiving relay being substantially neutralized by} the flow of the-inin the third Winding; In testimony whereof, I have signed my SAMUELI. CORY. 

